1. Field of the Invention
The present invention relate, for example, to a communication system constituted by a communication terminal apparatus such as a mobile telephone terminal or a wireless key apparatus restricting the operation of the mobile telephone terminal and to a communication terminal apparatus constituting the communication system.
2. Description of the Related Art
In recent years, a mobile telephone terminal which is one of communication terminal apparatuses a user always taking along in possession has a trend such that various functions other than wireless telephone functions of primary functions are built-in so as to contain multi functions.
For example, there exists such a terminal in which a camera function carrying out a filming of a still picture and a moving picture, a recording and reproducing function of music data, a viewing and listening function of television broadcast or the like is built-in.
In addition, there has been developed a mobile telephone. terminal in which a function as a non-contacting IC card which has been prevailing rapidly in recent years is built-in. This non-contacting IC card is utilized as a boarding ticket of transport facilities, a membership card, an employee ID card, a card for price settlement means at a shop or the like where an authentication process is carried out by performing wireless communication between adjacent reader and writer, so that it is easy-to-use as compared with a magnetic card or the like. It should be noted in a case when an IC card function unit is mounted in a mobile terminal that the IC card function unit is not always necessarily to have a card type shape.
And now, it is preferable for the mobile telephone terminal having multi functions in this manner to be carried out with a process in order to secure some kind or another security for preventing various functions provided in the terminal from being abused when the terminal is lost. In particular, utilization in personal authentication, settlement or the like is assumed in case of a terminal equipped with an IC card function and there is a dangerous possibility that personal information stored in a memory of an IC chip is read out unjustly or unjust settlement or the like is carried out, so that the necessity for a function for is preventing the unjust use thereof is high. There are descriptions, for example, in Japanese Jap. laid-open patent publication No. 2001-352579 or No. 2001-358827 that a wireless card which forms a pair with respect to the mobile telephone terminal is prepared and authentication request is wireless-transmitted periodically from that wireless card such that the functions of mobile telephone terminal is made to be restricted in a case when collation with respect to the authentication request cannot be taken.
More specifically, in a case when the mobile telephone terminal and the wireless card exchange ID (identification information) inherent therein periodically and a favorable communication state is maintained, that is, in a case when the ID exchange is realized, the mobile telephone terminal carries out a normal operation. On the contrary, when it is a state where the ID cannot be exchanged, that is, when the communication state is deteriorated or the communication is cut off, the use of partial function in the mobile telephone terminal is to be limited. In other words, it is possible to execute function limitation after presuming a distance between the mobile telephone terminal and the wireless card by utilizing wireless communication characteristics such that a favorable communication is possible when communication distance between the mobile telephone terminal and the wireless card is short and the communication state becomes deteriorated when the communication distance becomes long.